We fished Poco out at Hoover, Boomvang and Nancen, we only saw 3 marlin and 3 tuna in 2 days of fishing. We had noticed that the last couple of tuna trips this year to the floaters were without yellow fin and few black fin tuna. What we did find during Poco is the cause of this poor fishing, longlines. We followed one from Nancen for ten miles without finding the end!! We did mark numerous large fish(marlin?, big yellowfin?, sharks?) hooked on the line at 75' as we ran down the set. Several other boats reported longlines in other areas of the Texas shelf. No qualifying marlin were caught by the 90 offshore boats that fished Poco along the entire Texas coast!!! We did not know if the set we encountered was legal as it had no identification markings on it. Does anyone know the rules for longlines off the Texas coast? Legal or illegal this practice has to stop as it has destroyed the deep water fishery off our coast.